Input Unit Arrangement

ABSTRACT

An input unit arrangement for controlling an electronic device is provided. The arrangement comprises: a base; a position-coding pattern provided on the base and coding a first and second sets of absolute positions on spatially separate areas of the base. the first and second sets of absolute positions being mutually exclusive and coded by spatially separate first and second subsets of the position-coding pattern; a handheld image-recording device for recording images of the position-coding pattern; and a processor for deriving a position from the position coding pattern in the recorded image, the processor providing an instruction to the electronic device to perform a first function when the absolute position belongs to the first set, and a second function when the absolute position belongs to the second set. The arrangement enables a user to select different functions by selecting differing areas of the base on which the position-coding pattern is provided.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 11/159,169 filed onJun. 23, 2005, which is continuation of U.S. application Ser. No.09/693,515 filed on Oct. 20, 2000, now issued U.S. Pat. No. 6,965,454,the entire contents of which are herein incorporated by reference.

FIELD OF INVENTION

The present invention relates generally to computing systems and, moreparticularly, to a method and system for enabling graphic design bymeans of a computer system. It has specific application to the operationof a computer system involving a printed form-based user interface.

CO-PENDING APPLICATIONS

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Oct. 20,2000: 09/693415 7110126 6813558 6965454 6847883 7131058 09/6936906982798 6474888 6627870 6724374 09/693514 6454482 6808330 65273656474773 6550997

The disclosures of these co-pending applications are incorporated hereinby cross-reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Sep. 15,2000: 6679420 6963845 6995859 6720985

The disclosures of these co-pending applications are incorporated hereinby cross-reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-pending applications/granted patentsfiled by the applicant or assignee of the present invention on Jun. 30,2000: 6824044 6678499 6976220 6976035 6766942 09/609303 6922779 697801909/607843 6959298 6973450 7150404 6965882 09/608022 7007851 69579216457883 6831682 6977751 6398332 6394573 6622923The disclosures of these co-pending applications are incorporated hereinby cross-reference.

Various methods, systems and apparatus relating to the present inventionare disclosed in the following co-applications/granted patents filed bythe applicant or assignee of the present invention on 23 May 2000:6428133 6526658 6315399 6338548 6540319 6328431 6328425 6991320 63838336464332 6390591 7018016 6328417 09/575197 7079712 09/575123 682594509/575165 6813039 6987506 7038797 6980318 6816274 7102772 09/5751866681045 6728000 7173722 7088459 09/575181 7068382 7062651 67891946789191 6644642 6502614 6622999 6669385 6549935 6987573 6727996 65918846439706 6760119 09/575198 6290349 6428155 6785016 6870966 68226396737591 7055739 09/575129 6830196 6832717 6957768 09/575162 09/5751727170499 7106888 7123239 6409323 6281912 6604810 6318920 6488422 67952157154638 6859289

The disclosures of these co-pending applications are incorporated hereinby cross-reference.

BACKGROUND

Virtually since the advent of graphical user interfaces for computersystems have applications been available which enable the user to createand edit graphic images, and such applications have achieved anextremely high level of sophistication. In the context of drawing andpainting applications, computer monitors are able to displaytwo-dimensional graphic representations of image elements which areinputted or controlled by the user via a pointer or cursor function.Conventionally, the pointer or cursor function is operated by means of amouse, and the user is able to select from a number of available menusattributes of freehand drawing and painting strokes produced by movementof the mouse, such as pen or brush thickness and ink/paint color. Inaddition, the user can select and insert objects such as prescribedshapes and drawing/painting elements, text, images, paint fill, etc.Once an image has been produced, the user is able to edit it as desiredusing a suite of available editing functions, and the final image canthen be printed by way of appropriate available printing means. Users ofsuch applications range from, at one end of the scale, a graphicdesigner using a professional graphic design suite, allowing renderingand manipulation of two-dimensional images of complex 3D objects, to anoperator conversing with a client or colleague, who simply wishes tocommunicate an idea of interest in graphic form. In the lattersituation, the operator can sketch an idea using the computerapplication, and then send the sketch via, for example, electronic mail.

Further advances on the above concept have evolved with the developmentof computer peripheral devices such as touch screen displays and displayoverlays, and so-called electronic sketchpads. The latter devices employsensing digitizer tablets, based on any of a number of alternativesensing technologies such as resistive, capacitive and acoustictechniques. The operator uses an appropriate stylus on the tablet toinput freehand strokes, and presses ‘buttons’ on the tablet to selectfrom various objects, attributes and commands, which actions result instrokes and objects appearing in real time in an image on the operator'scomputer display. This type of system has the evident advantage that itis able to far more closely simulate the graphic designer's desktopenvironment and drawing tools.

SUMMARY OF INVENTION

It is an objective of the present invention to provide a method andsystem for enabling graphic design by means of a computer system.

According to the present invention in a first aspect, there is provideda method of enabling graphic design by means of a computer system, themethod including the steps of:

printing on demand, on a surface, a form containing information relatingto a graphic design activity, and at the same time as printing saidinformation, printing on the surface coded data indicative of anidentity of the form and of at least one reference point of the form;

receiving, in a computer system, indicating data from a sensing deviceregarding the identity of the form and a position of the sensing devicerelative to the form, the sensing device, when placed in an operativeposition relative to the form, sensing the indicating data using atleast some of the coded data; and

identifying, in the computer system and from the indicating data, atleast one parameter relating to the graphic design activity.

According to the present invention in a second aspect, there is provideda method of enabling graphic design by means of a computer system, themethod including the steps of:

printing on demand, on a surface, a form containing information relatingto a graphic design activity, and at the same time as printing theinformation, printing on the surface coded data indicative of at leastone parameter of the graphic design activity;

receiving, in a computer system, data from a sensing device regardingsaid at least one parameter and regarding movement of the sensing devicerelative to the form, the sensing device, when moved relative to theform, sensing the data regarding said at least one parameter using atleast some of the coded data and generating the data regarding its ownmovement relative to the form; and

interpreting, in the computer system, said movement of the sensingdevice as it relates to said at least one parameter.

According to the present invention in a third aspect, there is provideda system for enabling graphic design by means of a computer system,including:

a form printed on a surface, the form containing information relating toa graphic design activity, the form including coded data indicative ofan identity of the form and of at least one reference point of the form;

a printer operative to print on demand the form by printing on thesurface the information and at the same time the coded data; and

a computer system for receiving indicating data from a sensing devicefor identifying at least one parameter relating to the graphic designactivity, the indicating data being indicative of the identity of theform and a position of the sensing device relative to the form, thesensing device sensing the indicating data using at least some of thecoded data.

According to the present invention in a fourth aspect, there is provideda system for enabling graphic design by means of a computer system,including:

a form printed on a surface, the form containing information relating toa graphic design activity, the form including coded data indicative ofat least one parameter of the graphic design activity;

a printer operative to print on demand the form by printing on thesurface the information and at the same time the coded data; and

a computer system for receiving data from a sensing device regardingsaid at least one parameter and regarding movement of the sensing devicerelative to the form, and for interpreting said movement of the sensingdevice as it relates to said at least one parameter, the sensing device,when moved relative to the form, sensing the data regarding said atleast one parameter using at least some of the coded data and generatingthe data regarding its own movement relative to the form.

Accordingly, the present invention provides a method and system whichutilizes one or more forms capable of interacting with a computersystem. Whilst the novel method and system of the present invention maybe used in conjunction with a single computer system, in a particularlypreferred form it is designed to operate over a computer network, suchas the Internet.

Physically, the form is disposed on a surface medium which may be of anysuitable structure. However, in a preferred embodiment, the form isdisposed on sheet material such as paper or the like which has the codeddata printed on it and which allows interaction with the computersystem. The coded data is detectable preferably, but not exclusively,outside the visible spectrum, thereby enabling it to be machine-readablebut substantially invisible to the human eye. The form may also includevisible material which provides information to a user, such as theapplication or purpose of the form, and which visible information may beregistered or correlate in position with the relevant hidden coded data.

The system also includes a sensing device to convey data from the formto the computer system, and in some instances, to contribute additionaldata. Again, the sensing device may take a variety of forms but ispreferably compact and easily portable. In a particularly preferredarrangement, the sensing device is configured as a pen which is designedto be able to physically mark the interactive form as well as toselectively enable the coded data from the form to be read andtransmitted to the computer system. The coded data then provides controlinformation, configured such that designation thereof by a user causesinstructions to be applied to the software running on the computersystem or network.

The nature of the interaction between the form and the sensing deviceand the data that each contributes to the computer system may vary. Inone arrangement, the coded data on the form is indicative of theidentity of the form and of at least one reference point on that form.In another embodiment, the interactive form includes coded data which isindicative of a parameter of the form, whereas the sensing device isoperative to provide data regarding its own movement relative to thatform to the computer system together with coded data from the form. Inyet another arrangement, the form includes the coded data which at leastidentifies the form, and the sensing device is designed to provide, tothe computer system, data based on the form coded data, and also on datawhich identifies the user of the device.

In a preferred arrangement, the system and method also employs speciallydesigned printers to print the interactive form. Further these printersconstitute or form part of the computer system and are designed toreceive data from the sensing device. As indicated above, the system andmethod of the invention is ideally suited to operate over a network. Inthis arrangement, the printers are fully integrated into the network andallow for printing of the interactive forms on demand and also fordistributing of the forms using a mixture of multicast and pointcastcommunication protocols.

Accordingly, in a preferred form, the present invention provides methodsand systems which use a paper and pen based interface for a computersystem. This provides many significant benefits over traditionalcomputer systems. The advantage of paper is that it is widely used todisplay and record information. Further, printed information is easierto read than information displayed on a computer screen. Moreover, paperdoes not run on batteries, can be read in bright light, or robustlyaccepts coffee spills or the like and is portable and disposable.Furthermore, the system allows for hand-drawing and hand-writing to becaptured which affords greater richness of expression than input via acomputer keyboard and mouse.

BRIEF DESCRIPTION OF DRAWINGS

Preferred and other embodiments of the invention will now be described,by way of non-limiting example only, with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic of a the relationship between a sample printednetpage and its online page description;

FIG. 2 is a schematic view of a interaction between a netpage pen, anetpage printer, a netpage page server, and a netpage applicationserver;

FIG. 3 is a schematic view of a high-level structure of a printednetpage and its online page description;

FIG. 4 a is a plan view showing a structure of a netpage tag;

FIG. 4 b is a plan view showing a relationship between a set of the tagsshown in FIG. 4 a and a field of view of a netpage sensing device in theform of a netpage pen;

FIG. 5 a is a plan view showing an alternative structure of a netpagetag;

FIG. 5 b is a plan view showing a relationship between a set of the tagsshown in FIG. 5 a and a field of view of a netpage sensing device in theform of a netpage pen;

FIG. 5 c is a plan view showing an arrangement of nine of the tags shownin FIG. 5 a where targets are shared between adjacent tags;

FIG. d is a plan view showing the interleaving and rotation of thesymbols of the four codewords of the tag shown in FIG. 5 a;

FIG. 6 is a schematic view of a set of user interface flow documenticons;

FIG. 7 is a schematic view of a set of user interface page layoutelement icons;

FIG. 8 is a class diagram representing a system according to theinvention;

FIG. 9 is a drawing element class diagram;

FIG. 10 is two-dimensional transform class diagram;

FIG. 11 is a drawing object class diagram;

FIG. 12 is a color texture class diagram;

FIG. 13 is an opacity texture class diagram;

FIG. 14 is a shape class diagram;

FIG. 15 is a shape element class diagram;

FIG. 16 is a constructive planar geometry (CPG) operator class diagram;

FIG. 17 is a current settings class diagram;

FIG. 18 illustrates a nib style setting protocol;

FIG. 19 illustrates a Drawing and Painting Main Page user interfaceflow;

FIG. 20 shows a Modal Drawing page;

FIG. 21 shows a Modal Palette; and

FIG. 22 shows a Modeless Drawing Page.

DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Note: Memjet™ is a trademark of Silverbrook Research Pty Ltd, Australia.

In the preferred embodiment, the invention is configured to work withthe netpage networked computer system, a summary of which is given belowand a detailed description of which is given in our earlierapplications, including in particular applications U.S. Ser. No.09/575,129, U.S. Ser. No. 09/575,174, U.S. Ser. No. 09/575,155, U.S.Ser. No. 09/575,195 and U.S. Ser. No. 09/575,141. It will be appreciatedthat not every implementation will necessarily embody all or even mostof the specific details and extensions described in these applicationsin relation to the basic system. However, the system is described in itsmost complete form to assist in understanding the context in which thepreferred embodiments and aspects of the present invention operate.

In brief summary, the preferred form of the netpage system employs acomputer interface in the form of a mapped surface, that is, a physicalsurface which contains references to a map of the surface maintained ina computer system. The map references can be queried by an appropriatesensing device. Depending upon the specific implementation, the mapreferences may be encoded visibly or invisibly, and defined in such away that a local query on the mapped surface yields an unambiguous mapreference both within the map and among different maps. The computersystem can contain information about features on the mapped surface, andsuch information can be retrieved based on map references supplied by asensing device used with the mapped surface. The information thusretrieved can take the form of actions which are initiated by thecomputer system on behalf of the operator in response to the operator'sinteraction with the surface features.

In its preferred form, the netpage system relies on the production of,and human interaction with, netpages. These are pages of text, graphicsand images printed on ordinary paper or other media, but which work likeinteractive web pages. Information is encoded on each page using inkwhich is substantially invisible to the unaided human eye. The ink,however, and thereby the coded data, can be sensed by an opticallyimaging pen and transmitted to the netpage system.

In the preferred form, active buttons and hyperlinks on each page can beclicked with the pen to request information from the network or tosignal preferences to a network server. In one embodiment, text writtenby hand on a netpage is automatically recognized and converted tocomputer text in the netpage system, allowing forms to be filled in. Inother embodiments, signatures recorded on a netpage are automaticallyverified, allowing e-commerce transactions to be securely authorized.

As illustrated in FIG. 1, a printed netpage 1 can represent ainteractive form which can be filled in by the user both physically, onthe printed page, and “electronically”, via communication between thepen and the netpage system. The example shows a “Request” formcontaining name and address fields and a submit button. The netpageconsists of graphic data 2 printed using visible ink, and coded data 3printed as a collection of tags 4 using invisible ink. The correspondingpage description 5, stored on the netpage network, describes theindividual elements of the netpage. In particular it describes the typeand spatial extent (zone) of each interactive element (i.e. text fieldor button in the example), to allow the netpage system to correctlyinterpret input via the netpage. The submit button 6, for example, has azone 7 which corresponds to the spatial extent of the correspondinggraphic 8.

As illustrated in FIG. 2, the netpage pen 101, a preferred form of whichis described in our earlier application U.S. Ser. No. 09/575,174, worksin conjunction with a netpage printer 601, an Internet-connectedprinting appliance for home, office or mobile use. The pen is wirelessand communicates securely with the netpage printer via a short-rangeradio link 9.

The netpage printer 601, preferred forms of which are described in ourearlier application U.S. Ser. No. 09/575,155 and our co-filedapplication U.S. Ser. No. 09/693,514, is able to deliver, periodicallyor on demand, personalized newspapers, magazines, catalogs, brochuresand other publications, all printed at high quality as interactivenetpages. Unlike a personal computer, the netpage printer is anappliance which can be, for example, wall-mounted adjacent to an areawhere the morning news is first consumed, such as in a user's kitchen,near a breakfast table, or near the household's point of departure forthe day. It also comes in tabletop, desktop, portable and miniatureversions.

Netpages printed at their point of consumption combine the ease-of-useof paper with the timeliness and interactivity of an interactive medium.

As shown in FIG. 2, the netpage pen 101 interacts with the coded data ona printed netpage 1 and communicates, via a short-range radio link 9,the interaction to a netpage printer. The printer 601 sends theinteraction to the relevant netpage page server 10 for interpretation.In appropriate circumstances, the page server sends a correspondingmessage to application computer software running on a netpageapplication server 13. The application server may in turn send aresponse which is printed on the originating printer.

The netpage system is made considerably more convenient in the preferredembodiment by being used in conjunction with high-speedmicroelectromechanical system (MEMS) based inkjet (Memjet™) printers,for example as described in our earlier application U.S. Ser. No.09/575,141. In the preferred form of this technology, relativelyhigh-speed and high-quality printing is made more affordable toconsumers. In its preferred form, a netpage publication has the physicalcharacteristics of a traditional newsmagazine, such as a set ofletter-size glossy pages printed in full color on both sides, boundtogether for easy navigation and comfortable handling.

The netpage printer exploits the growing availability of broadbandInternet access. The netpage printer can also operate with slowerconnections, but with longer delivery times and lower image quality. Thenetpage system can also be enabled using existing consumer inkjet andlaser printers, although the system will operate more slowly and willtherefore be less acceptable from a consumer's point of view. In otherembodiments, the netpage system is hosted on a private intranet. Instill other embodiments, the netpage system is hosted on a singlecomputer or computer-enabled device, such as a printer.

Netpage publication servers 45 on the netpage network are configured todeliver print-quality publications to netpage printers. Periodicalpublications are delivered automatically to subscribing netpage printersvia pointcasting and multicasting Internet protocols. Personalizedpublications are filtered and formatted according to individual userprofiles.

A netpage printer can be configured to support any number of pens, and apen can work with any number of netpage printers. In the preferredimplementation, each netpage pen has a unique identifier. A householdmay have a collection of colored netpage pens, one assigned to eachmember of the family. This allows each user to maintain a distinctprofile with respect to a netpage publication server or applicationserver.

A netpage pen can also be registered with a netpage registration server11 and linked to one or more payment card accounts. This allowse-commerce payments to be securely authorized using the netpage pen. Thenetpage registration server compares the signature captured by thenetpage pen with a previously registered signature, allowing it toauthenticate the user's identity to an e-commerce server. Otherbiometrics can also be used to verify identity. A version of the netpagepen includes fingerprint scanning, verified in a similar way by thenetpage registration server.

Although a netpage printer may deliver periodicals such as the morningnewspaper without user intervention, it can be configured never todeliver unsolicited junk mail. In its preferred form, it only deliversperiodicals from subscribed or otherwise authorized sources. In thisrespect, the netpage printer is unlike a fax machine or e-mail accountwhich is visible to any junk mailer who knows the telephone number ore-mail address.

Each object model in the system is described using a Unified ModelingLanguage (UML) class diagram. A class diagram consists of a set ofobject classes connected by relationships, and two kinds ofrelationships are of interest here: associations and generalizations. Anassociation represents some kind of relationship between objects, i.e.between instances of classes. A generalization relates actual classes,and can be understood in the following way: if a class is thought of asthe set of all objects of that class, and class A is a generalization ofclass B, then B is simply a subset of A. Each class is drawn as arectangle labelled with the name of the class. It contains a list of theattributes of the class, separated from the name by a horizontal line,and a list of the operations of the class, separated from the attributelist by a horizontal line. In the class diagrams which follow, however,operations are never modelled. An association is drawn as a line joiningtwo classes, optionally labelled at either end with the multiplicity ofthe association. The default multiplicity is one. An asterisk (*)indicates a multiplicity of “many”, i.e. zero or more. Each associationis optionally labelled with its name, and is also optionally labelled ateither end with the role of the corresponding class. An open diamondindicates an aggregation association (“is-part-of”), and is drawn at theaggregator end of the association line. A generalization relationship(“is-a”) is drawn as a solid line joining two classes, with an arrow (inthe form of an open triangle) at the generalization end. When a classdiagram is broken up into multiple diagrams, any class which isduplicated is shown with a dashed outline in all but the main diagramwhich defines it. It is shown with attributes only where it is defined.

Netpages are the foundation on which a netpage network is built. Theyprovide a paper-based user interface to published information andinteractive services. A netpage consists of a printed page (or othersurface region) invisibly tagged with references to an onlinedescription of the page. The online page description is maintainedpersistently by a netpage page server. The page description describesthe visible layout and content of the page, including text, graphics andimages. It also describes the input elements on the page, includingbuttons, hyperlinks, and input fields. A netpage allows markings madewith a netpage pen on its surface to be simultaneously captured andprocessed by the netpage system.

Multiple netpages can share the same page description. However, to allowinput through otherwise identical pages to be distinguished, eachnetpage is assigned a unique page identifier. This page ID hassufficient precision to distinguish between a very large number ofnetpages.

Each reference to the page description is encoded in a printed tag. Thetag identifies the unique page on which it appears, and therebyindirectly identifies the page description. The tag also identifies itsown position on the page. Characteristics of the tags are described inmore detail below.

Tags are printed in infrared-absorptive ink on any substrate which isinfrared-reflective, such as ordinary paper. Near-infrared wavelengthsare invisible to the human eye but are easily sensed by a solid-stateimage sensor with an appropriate filter.

A tag is sensed by an area image sensor in the netpage pen, and the tagdata is transmitted to the netpage system via the nearest netpageprinter. The pen is wireless and communicates with the netpage printervia a short-range radio link. Tags are sufficiently small and denselyarranged that the pen can reliably image at least one tag even on asingle click on the page. It is important that the pen recognize thepage ID and position on every interaction with the page, since theinteraction is stateless. Tags are error-correctably encoded to makethem partially tolerant to surface damage.

The netpage page server maintains a unique page instance for eachprinted netpage, allowing it to maintain a distinct set of user-suppliedvalues for input fields in the page description for each printednetpage.

The relationship between the page description, the page instance, andthe printed netpage is shown in FIG. 3. The printed netpage may be partof a printed netpage document 14. The page instance is associated withboth the netpage printer which printed it and, if known, the netpageuser who requested it.

In a preferred form, each tag identifies the region in which it appears,and the location of that tag within the region. A tag may also containflags which relate to the region as a whole or to the tag. One or moreflag bits may, for example, signal a tag sensing device to providefeedback indicative of a function associated with the immediate area ofthe tag, without the sensing device having to refer to a description ofthe region. A netpage pen may, for example, illuminate an “active area”LED when in the zone of a hyperlink.

In a preferred embodiment, each tag contains an easily recognizedinvariant structure which aids initial detection, and which assists inminimizing the effect of any warp induced by the surface or by thesensing process. The tags preferably tile the entire page, and aresufficiently small and densely arranged that the pen can reliably imageat least one tag even on a single click on the page. It is importantthat the pen recognize the page ID and position on every interactionwith the page, since the interaction is stateless.

In a preferred embodiment, the region to which a tag refers coincideswith an entire page, and the region ID encoded in the tag is thereforesynonymous with the page ID of the page on which the tag appears. Inother embodiments, the region to which a tag refers can be an arbitrarysubregion of a page or other surface. For example, it can coincide withthe zone of an interactive element, in which case the region ID candirectly identify the interactive element.

Each tag contains typically contains 16 bits of tag ID, at least 90 bitsof region ID, and a number of flag bits. Assuming a maximum tag densityof 64 per square inch, a 16-bit tag ID supports a region size of up to1024 square inches. Larger regions can be mapped continuously withoutincreasing the tag ID precision simply by using abutting regions andmaps. The distinction between a region ID and a tag ID is mostly one ofconvenience. For most purposes the concatenation of the two can beconsidered as a globally unique tag ID. Conversely, it may also beconvenient to introduce structure into the tag ID, for example to definethe x and y coordinates of the tag. A 90-bit region ID allows 2⁹⁰ (˜10²⁷or a thousand trillion trillion) different regions to be uniquelyidentified. Tags may also contain type information, and a region may betagged with a mixture of tag types. For example, a region may be taggedwith one set of tags encoding x coordinates and another set, interleavedwith the first, encoding y coordinates.

In one embodiment, 120 bits of tag data are redundantly encoded using a(15, 5) Reed-Solomon code. This yields 360 encoded bits consisting of 6codewords of 15 4-bit symbols each. The (15, 5) code allows up to 5symbol errors to be corrected per codeword, i.e. it is tolerant of asymbol error rate of up to 33% per codeword. Each 4-bit symbol isrepresented in a spatially coherent way in the tag, and the symbols ofthe six codewords are interleaved spatially within the tag. This ensuresthat a burst error (an error affecting multiple spatially adjacent bits)damages a minimum number of symbols overall and a minimum number ofsymbols in any one codeword, thus maximising the likelihood that theburst error can be fully corrected.

Any suitable error-correcting code code can be used in place of a (15,5) Reed-Solomon code, for example a Reed-Solomon code with more or lessredundancy, with the same or different symbol and codeword sizes;another block code; or a different kind of code, such as a convolutionalcode (see, for example, Stephen B. Wicker, Error Control Systems forDigital Communication and Storage, Prentice-Hall 1995, the contents ofwhich a herein incorporated by cross-reference).

One embodiment of the physical representation of the tag, shown in FIG.4 a and described in our earlier application U.S. Ser. No. 09/575,129,includes fixed target structures 15, 16, 17 and variable data areas 18.The fixed target structures allow a sensing device such as the netpagepen to detect the tag and infer its three-dimensional orientationrelative to the sensor. The data areas contain representations of theindividual bits of the encoded tag data. To maximise its size, each databit is represented by a radial wedge in the form of an area bounded bytwo radial lines and two concentric circular arcs. Each wedge has aminimum dimension of 8 dots at 1600 dpi and is designed so that its base(its inner arc), is at least equal to this minimum dimension. The heightof the wedge in the radial direction is always equal to the minimumdimension. Each 4-bit data symbol is represented by an array of 2×2wedges. The fifteen 4-bit data symbols of each of the six codewords areallocated to the four concentric symbol rings 18 a to 18 d ininterleaved fashion. Symbols are allocated alternately in circularprogression around the tag. The interleaving is designed to maximise theaverage spatial distance between any two symbols of the same codeword.

In order to support “single-click” interaction with a tagged region viaa sensing device, the sensing device must be able to see at least oneentire tag in its field of view no matter where in the region or at whatorientation it is positioned. The required diameter of the field of viewof the sensing device is therefore a function of the size and spacing ofthe tags. Assuming a circular tag shape, the minimum diameter of thesensor field of view 193 is obtained when the tags are tiled on aequilateral triangular grid, as shown in FIG. 4 b.

The tag structure just described is designed to allow both regulartilings of planar surfaces and irregular tilings of non-planar surfaces.Regular tilings are not, in general, possible on non-planar surfaces. Inthe more usual case of planar surfaces where regular tilings of tags arepossible, i.e. surfaces such as sheets of paper and the like, moreefficient tag structures can be used which exploit the regular nature ofthe tiling.

An alternative tag structure more suited to a regular tiling is shown inFIG. 5 a. The tag 4 is square and has four perspective targets 17. It issimilar in structure to tags described by Bennett et al. in U.S. Pat.No. 5,051,746. The tag represents sixty 4-bit Reed-Solomon symbols 47,for a total of 240 bits. The tag represents each one bit as a dot 48,and each zero bit by the absence of the corresponding dot. Theperspective targets are designed to be shared between adjacent tags, asshown in FIGS. 5 b and 5 c. FIG. 5 b shows a square tiling of 16 tagsand the corresponding minimum field of view 193, which must span thediagonals of two tags. FIG. 5 c shows a square tiling of nine tags,containing all one bits for illustration purposes.

Using a (15, 7) Reed-Solomon code, 112 bits of tag data are redundantlyencoded to produce 240 encoded bits. The four codewords are interleavedspatially within the tag to maximize resilience to burst errors.Assuming a 16-bit tag ID as before, this allows a region ID of up to 92bits. The data-bearing dots 48 of the tag are designed to not overlaptheir neighbors, so that groups of tags cannot produce structures whichresemble targets. This also saves ink. The perspective targets thereforeallow detection of the tag, so further targets are not required.

Although the tag may contain an orientation feature to allowdisambiguation of the four possible orientations of the tag relative tothe sensor, it is also possible to embed orientation data in the tagdata. For example, the four codewords can be arranged so that each tagorientation contains one codeword placed at that orientation, as shownin FIG. 5 d, where each symbol is labelled with the number of itscodeword (1-4) and the position of the symbol within the codeword (A-O).Tag decoding then consists of decoding one codeword at each orientation.Each codeword can either contain a single bit indicating whether it isthe first codeword, or two bits indicating which codeword it is. Thelatter approach has the advantage that if, say, the data content of onlyone codeword is required, then at most two codewords need to be decodedto obtain the desired data. This may be the case if the region ID is notexpected to change within a stroke and is thus only decoded at the startof a stroke. Within a stroke only the codeword containing the tag ID isthen desired. Furthermore, since the rotation of the sensing devicechanges slowly and predictably within a stroke, only one codewordtypically needs to be decoded per frame.

It is possible to dispense with perspective targets altogether andinstead rely on the data representation being self-registering. In thiscase each bit value (or multi-bit value) is typically represented by anexplicit glyph, i.e. no bit value is represented by the absence of aglyph. This ensures that the data grid is well-populated, and thusallows the grid to be reliably identified and its perspective distortiondetected and subsequently corrected during data sampling. To allow tagboundaries to be detected, each tag data must contain a marker pattern,and these must be redundantly encoded to allow reliable detection. Theoverhead of such marker patterns is similar to the overhead of explicitperspective targets. One such scheme uses dots positioned a variouspoints relative to grid vertices to represent different glyphs and hencedifferent multi-bit values (see Anoto Technology Description, AnotoApril 2000).

Decoding a tag results in a region ID, a tag ID, and a tag-relative pentransform. Before the tag ID and the tag-relative pen location can betranslated into an absolute location within the tagged region, thelocation of the tag within the region must be known. This is given by atag map, a function which maps each tag ID in a tagged region to acorresponding location. A tag map reflects the scheme used to tile thesurface region with tags, and this can vary according to surface type.When multiple tagged regions share the same tiling scheme and the sametag numbering scheme, they can also share the same tag map. The tag mapfor a region must be retrievable via the region ID. Thus, given a regionID, a tag ID and a pen transform, the tag map can be retrieved, the tagID can be translated into an absolute tag location within the region,and the tag-relative pen location can be added to the tag location toyield an absolute pen location within the region.

The tag ID may have a structure which assists translation through thetag map. It may, for example, encoded cartesian coordinates or polarcoordinates, depending on the surface type on which it appears. The tagID structure is dictated by and known to the tag map, and tag IDsassociated with different tag maps may therefore have differentstructures.

Two distinct surface coding schemes are of interest, both of which usethe tag structure described earlier in this section. The preferredcoding scheme uses “location-indicating” tags as already discussed. Analternative coding scheme uses “object-indicating” (or“function-indicating”) tags.

A location-indicating tag contains a tag ID which, when translatedthrough the tag map associated with the tagged region, yields a uniquetag location within the region. The tag-relative location of the pen isadded to this tag location to yield the location of the pen within theregion. This in turn is used to determine the location of the penrelative to a user interface element in the page description associatedwith the region. Not only is the user interface element itselfidentified, but a location relative to the user interface element isidentified. Location-indicating tags therefore trivially support thecapture of an absolute pen path in the zone of a particular userinterface element.

An object-indicating (or function-indicating) tag contains a tag IDwhich directly identifies a user interface element in the pagedescription associated with the region (or equivalently, a function).All the tags in the zone of the user interface element identify the userinterface element, making them all identical and thereforeindistinguishable. Object-indicating tags do not, therefore, support thecapture of an absolute pen path. They do, however, support the captureof a relative pen path. So long as the position sampling frequencyexceeds twice the encountered tag frequency, the displacement from onesampled pen position to the next within a stroke can be unambiguouslydetermined. As an alternative, the netpage pen 101 can contain a pair ormotion-sensing accelerometers, as described in our earlier applicationU.S. Ser. No. 09/575,174.

With either tagging scheme, the tags function in cooperation withassociated visual elements on the netpage as user interactive elementsin that a user can interact with the printed page using an appropriatesensing device in order for tag data to be read by the sensing deviceand for an appropriate response to be generated in the netpage system.

Each application user interface flow is illustrated as a collection ofdocuments linked by command arrows. A command arrow indicates that thetarget document is printed as a result of the user pressing thecorresponding command button on the source page. Some command arrows arelabelled with multiple commands separated by slashes (‘/’s), indicatingthat any one of the specified commands causes the target document to beprinted. Although multiple commands may label the same command arrow,they typically have different side-effects.

In application terms, it is important to distinguish between netpagedocuments and netpage forms. Documents contain printed information, aswell as command buttons which can be pressed by the user to requestfurther information or some other action. Forms, in addition to behavinglike normal documents, also contain input fields which can be filled inby the user. They provide the system with a data input mechanism. It isalso useful to distinguish between documents which contain genericinformation and documents which contain information specific to aparticular interaction between the user and an application. Genericdocuments may be pre-printed publications such as magazines sold at newsstands or advertising posters encountered in public places. Forms mayalso be pre-printed, including, for example, subscription formsencountered in pre-printed publications. They may, of course, also begenerated on-the-fly by a netpage printer in response to user requests.User-specific documents and forms are normally generated on the fly by anetpage printer in response to user requests. FIG. 6 shows a genericdocument 990, a generic form 991, a user-specific document 992, and auser-specific form 993.

Netpages which participate in a user interface flow are furtherdescribed by abstract page layouts. A page layout may contain variouskinds of elements, each of which has a unique style to differentiate itfrom the others. As shown in FIG. 7, these include fixed information994, variable information 995, input fields 996, command buttons 997,draggable commands 998, and text hyperlinks or hypertext links 999.

When a user interface flow is broken up into multiple diagrams, anydocument which is duplicated is shown with dashed outlines in all butthe main diagram which defines it.

DRAWING AND PAINTING USING THE NETPAGE SYSTEM

The marking nib of a netpage pen is typically a ballpoint which producesa fixed-width line of a single fixed color. Nevertheless, the netpagesystem can be used to draw and paint interactively using a variety ofline styles, colors, and brushes. Not unlike a drawing or paintingapplication in a conventional graphical user interface, the netpageapplication presents a palette of available styles which can be used todraw or paint in what is sometimes referred to as “2½ dimensions”, i.e.in two dimensions with depth ordering of objects. The colors and stylesused typically only become visible when the drawing or canvas page isreprinted, which generally takes place on demand.

Drawing & Painting Object Model

The Drawing and Painting object model revolves around a drawingprovider, a drawing user, and a drawing.

A drawing provider 500 has a provider identifier and a name. A drawingprovider 500 is typically associated with a number of drawing users 501,each of which has a unique alias identifier 65 and a name. A netpageuser 800 may of course be registered as a drawing user 501 with morethan one drawing provider 500. The drawing and painting applicationclass diagram is shown in FIG. 8.

A drawing user 501 typically has a number of drawings 502, each of whichhas a unique drawing identifier, as well as the date and time thedrawing was created. Associated with a drawing are a number of drawingelements 504, ordered by depth, and each drawing element 504 has atwo-dimensional (2D) transform 507, which comprises a translation, arotation, and a scale. The 2D Transform class diagram is shown in FIG.10. A drawing element 504 may be a group 505, containing one or moredrawing elements ordered by depth, or it may be a drawing object 506,and the Drawing Element class diagram of the netpage system is shown inFIG. 9.

A drawing object 506 has associated with it a shape 508, lineinformation 509 (optional) and fill information 510 (optional). Lineinformation 509 includes a line style 511, color texture 512, andopacity texture 513, whilst fill information 510 includes a colortexture 512 and an opacity texture 513. A color texture 512 contains a2D transform 507, and is either a color image 514, a scalar color 515,or a procedural color texture 516. An opacity texture 513 also containsa 2D transform 507, and is either an opacity image 517, a scalar opacity518, or a procedural opacity texture 519. The netpage drawing objectclass diagram is shown in FIG. 11, the netpage color texture classdiagram is shown in FIG. 12, and the netpage opacity texture classdiagram is shown in FIG. 13.

The shape class diagram is illustrated in FIG. 14. A shape 508 may be ashape element 521, or it may be a Constructive Planar Geometry (CPG)Operator 520 with two ordered shape elements 508. The CPG Operator 520describes an operation to be performed on the two shape elements 508,the basic CPG operators being union 528, intersection 529, anddifference 530. The shape order is important for the difference operator530. These operators are described in detail in the section entitled“Constructive Solid Geometry” in “3D Computer Graphics”, Alan Watt,Addison Wesley, 1993, the content of which is incorporated herein byreference. The CPG operator class diagram is shown in FIG. 16.

A shape element 521 contains a 2D transform 507, and can be a freehandobject 522 (with associated digital ink 873), text 523 (with the textstring and associated font settings 531), a polygon 524 (described by alist of points), an ellipse 525, an (elliptic) arc 526, or a curve 527.The Shape Element class diagram is shown in FIG. 15.

A polygon shape element 524 can specify an open polygon (polyline) or aclosed polygon, and in the latter case the start and end points in thepoint list are identical. An ellipse shape element 525 is defined as aunit circle centred at the origin, and the associated 2D transformallows the definition of an arbitrary ellipse. An arc shape element 526is similarly defined as a 90 degree arc of a unit circle in the firstquadrant. A curve 527 is made up of a number of Bézier segments and isdefined by a list of control points. It is to be noted that a drawingprovider may also support other object types.

The above object model supports user-specified objects as well asthird-party supplied objects (clip-art, graphics etc.).

The nib style 825 for a drawing object specifies the line (or pen)shape, size, color and texture, and is derived from the current nibstyle 825 associated with the netpage pen 801 being used. The netpagepen 801, nib style 825, and digital ink 873 are described in furtherdetail in our earlier application U.S. Ser. No. 09/575,174.

Associated with a drawing user 501 are the user's current settings 503(font setting, grid setting, handle setting, fill setting, paletteselection) for the drawing application. The font setting 531 records thefont name, size and style of the font last selected by the user. Thegrid setting 532 records whether to show or hide grid lines, the gridsize, and whether to snap objects to the grid. The handle setting 533records whether to show or hide object handles. The fill setting 534records the user's last selected fill color and opacity textures. Thepalette selection 535 records the standard object last selected from theobject palette by the user. The current settings class diagram is shownin FIG. 17.

Drawing & Painting User Interface

The user may obtain the Drawing and Painting main page 536 from avariety of links, such as the netpage directory (i.e. via the help menuof the user's netpage printer) and the netpage user's own bookmark.

DRAWING & PAINTING MAIN PAGE

The Drawing Main Page 536 allows the user to draw and manipulateobjects, and the Drawing Main Page user interface flow is illustrated inFIG. 19. The Drawing Main Page 536 comprises a drawing area, one or morepalettes, command icons, and buttons, and an example of a drawing pageis shown in FIG. 20.

The user can draw freehand objects, or can select standard objects froman object palette 544. The user can also write freehand text and, ifdesired, is able to convert it to text in a specified font. The user canselect the desired colors, brush styles and fill styles for objects andtext. Some operations can be modal, such as pen style selection, whileothers are not suited to modal operation (such as pasting an object) andso are modeless. When operating modally, the user selects brush, font,or other attributes from a palette by pressing the appropriate button onthe page with the netpage pen. This mode is used in subsequent drawingactions, but may not be visible until the page is reprinted. Whenoperating modelessly, the user applies attributes to a part of thedrawing after it is drawn.

Modeless operations are implemented using “dragging”, and the draggingaction may be performed using the non-marking nib or the marking nib.Dragging can be used to apply an attribute to an object, to drop anobject at a location, or to apply a command at a location. The startingpoint of the drag stroke is typically the command or palette icon, andthe ending point of the drag stroke is typically a desired location.These interaction techniques are described in further detail in ourearlier application U.S. Ser. No. 09/663,701.

Optionally the provider can expand the user interface to provide otherfunctionality or other interaction techniques.

Modal Operations

When operating modally, the user simply selects colors and styles, byclicking the appropriate button on the palette, and draws or “paints”(by drawing) in the usual way on the surface of the page. There may beno indication of the current mode (color, pen, brush, etc.), the drawingor painting consisting merely of fixed-width and fixed-color drawn linesuntil the page is reprinted. If the pen has a built-in display, such asan LCD feature, then the display can indicate the current mode.Alternatively, the pen may have an embedded electronically controlledcolor indicator, in which case the indicator displays the user-selectedcolor. This pen with color indicator is described in further detail inour co-filed application U.S. Ser. No. 09/693,216. There is no historyof mode changes on the page itself. An example of a Modal Drawing Page536 a using a modal palette is shown in FIG. 20, and an example ModalPalette Page 537 is shown in FIG. 21.

Modeless Operations

When operating modelessly, color, pen and brush attributes are appliedto a part of the picture after that part is drawn. Netpage provides oneway to support modeless pen attributes, by enabling the joining ofelements of the drawing to pen attributes in a palette using a lasso 541drawn with the pen. The tail of the lasso is joined to the attribute inthe palette, and the loop of the lasso circumscribes the part of thedrawing to which the attribute is being applied. When a marking pen isused, the lasso feature provides a graphical representation of applyingan attribute to a part of the drawing. Lassos can also be drawn with thepen in non-marking mode and a reprint can then be provided after eachattribute is applied, either automatically on completion of lassostroke, or on user request. Lassoing and related techniques aredescribed in further detail in our earlier application U.S. Ser. No.09/663,701.

An example of a drawing page with a modeless palette (Modeless DrawingPage 536 b) is shown in FIG. 22.

Object Handles

The user can choose to show handles on drawing objects by pressing the<Handles> button, in which case the drawing page is reprinted showingobject handles, the <Handles> button being replaced by a <No Handles>button. Each object's bounding box is displayed as a faint dottedrectangle around the object, and each object has two types of handles—scaling handles 539 (small squares appearing along the bounding box)and a rotation handle 540 (a line with a small circle at one endextending from the object's bounding box). The use of these handles isexplained in more detail below. An example of visible handles can beseen in the page example illustrated in FIG. 20.

Grid

The user can choose to display a grid on the drawing area by pressingthe <Show Grid> button, in which case the drawing page is reprintedshowing faint grid lines and with the <Show Grid> button replaced by a<Hide Grid> button.

The user can specify the size of the grid by pressing the desiredgrid-size button on the drawing palette, or by entering the desired gridsize in the grid size field (as shown in FIG. 22). If the user checksthe <Snap To Grid> checkbox, all objects drawn thereafter are snapped tothe grid. That is, any drawn object is repositioned and scaled so thatthe bounding box is aligned on the drawing's grid, whether the grid isvisible or not. When the drawing page is reprinted the object isre-positioned and the <Snap To Grid> checkbox is replaced by the <Don'tSnap To Grid> checkbox.

Manipulating Objects

The user can delete one or more objects by drawing a lasso starting atthe <Delete> icon, and circumscribing or otherwise indicating theobjects to be deleted. These objects are removed from the drawing whenthe page is reprinted.

The user can cut or copy one or more objects to their clipboard bydrawing a lasso starting at the <Cut> or <Copy> icon, and circumscribingthe objects to be cut or copied. Further, objects in the user'sclipboard, whether from the drawing application or another netpageapplication, can be pasted onto the drawing. The user draws a lasso fromthe <Paste> icon to the desired paste point on the drawing field, andthe pasted objects are shown next time the page is printed. Objects inthe user's clipboard may also be pasted into other drawing-relatedapplications.

Alternatively, the user is able to select content using the standardnetpage selection mechanism, enabling the user to copy content, pastecontent, or delete the selected content. These techniques are describedin further detail in our earlier application U.S. Ser. No. 09/663,640.

The user can move an object by drawing a stroke from inside the object,or from a point on the object's bounding box, to the desired location.The object is moved the length of the stroke, in the direction of thestroke. Further, the user can scale an object by drawing a stroke fromany of the object's scaling handles 539. The object is scaled so thatthe corresponding scaling handle on the scaled object is coincident withthe end of the user's stroke. If the stroke extends outside the object'sbounding box the object is scaled up (i.e. enlarged), and, conversely,if the stroke extends inside the object's bounding box the object isscaled down (i.e. shrunk). The user can rotate an object on the drawingin one of two ways. The user can select an object to rotate by drawing alasso from the <Rotate> icon and circumscribing the object(s), the userfirst entering the desired rotation, in degrees, in the <Deg> field. Therotation direction can be specified by signing the rotation angle, i.e.“+” indicates clockwise rotation and “−” indicates conterclockwiserotation. Alternatively, the user can rotate an object using theobject's rotation handle 540, whereby the user draws a stroke from theend of the rotation handle 540 to a point above (for anti-clockwiserotation) or below (for clockwise rotation) the rotation handle 540, toindicate the desired rotation.

Where objects overlap on a drawing the user can specify the relativedepth of the respective objects. To bring an object to the front of allother overlapping objects the user draws a lasso from the <To Front>icon circumscribing the object to move. Similarly, the user can send anobject to the back of a group of overlapping objects using the <To Back>icon. The user can bring an object forward one layer using the <MoveFwd> icon, and back one layer using the <Move Back> icon.

The user can zoom in on an area of the drawing by drawing a lasso fromthe <Zoom In> icon and circumscribing the area to be zoomed, resultingin the selected area being expanded to the largest possible size whilestill showing the entire selection within the drawing field. Similarly,the user can zoom out by drawing a lasso from the <Zoom Out> icon andcircumscribing an area into which the current visible drawing field isshown, the current visible drawing being then scaled down to the largestpossible size still fitting within the selected area. The current zoomlevel is shown in the <Zoom%> field.

Objects within a drawing may be grouped together to form a singleobject, by means of the user drawing a lasso from the <Group> icon andcircumscribing the objects to be grouped. The group may then be treatedas a single object, and if handles are shown, the group of objects willhave a single bounding box and a single rotation handle. Similarly,grouped objects can be ungrouped by drawing a lasso from the <Ungroup>icon and circumscribing the target group.

The user can apply a CPG operator to two objects by drawing a lasso fromthe CPG operator icon to the first object, and then a second lasso tothe second object. The order of selection of the two objects isimportant for the difference operator, <−>. The order of selection forunion, <+>, and intersection, <

>, is not important, i.e. either order produces the same results.

The user can convert all freehand drawn objects into standard objects byclicking the <Auto Tidy> button. The application converts each freehandobject into the closest matching standard object, and reprints thedrawing page.

The user can choose to reprint the drawing page, ignoring all newdrawing since the page was last printed, by pressing the <Reset Form>button. Further, the user can print a blank drawing form by pressing<New Form>, can print a palette page (shown in FIG. 21) by pressing the<Print Palette> button, can print the drawing field on a full page 538,without palettes, buttons or other netpage elements on the page, bypressing the <Print Full> button, and can print an updated drawing pageby pressing the <Update> button.

Text

The user can include text on the drawing by hand-writing the text at thedesired location on the drawing. The user then applies the <To Text>operation to the hand-writing, resulting in the conversion of thehand-writing to text. The text is tagged with the font setting from theuser's current settings, and the text is shown in this font when thepage is next printed.

Standard Objects

A user can readily include standard objects in a drawing, these standardobjects being chosen from a standard object palette 544 including iconsfor drawing a line, an (elliptic) arc, a rectangle, a rounded cornerrectangle, an ellipse, an open polygon (polyline), a closed polygon, anda curve. To include an object from the object palette 544 in thedrawing, the user draws a line from the object icon to a point withinthe drawing field. The specified drawing field is the object's centrefor an ellipse or arc. For all other standard objects, this pointspecifies the location of the bottom left corner of the object'sbounding box.

More typically, a user draws the desired object freehand, and thenconverts it to a standard object by drawing a lasso, starting at theobject palette icon and circumscribing the freehand object. The freehandobject is converted by the application to a standard object withattributes matching the freehand object as closely as possible.

To draw a straight line the user draws a line in the drawing field, andthen draws a lasso starting from the line icon and circumscribing thehand-drawn line. The line is then converted from a freehand object to atwo-point polyline object with start and end points matching those drawnby the user.

To draw an arc the user draws an arc in the drawing field, and thendraws a lasso starting from the arc icon and circumscribing thehand-drawn arc. The arc is then converted from a freehand object to anarc object with start and end points matching those drawn by the user.

To draw a rectangle (or rounded-corner rectangle) the user draws arectangle in the drawing field, and then draws a lasso starting from therectangle (or rounded-corner rectangle) icon and circumscribing thehand-drawn rectangle. The rectangle is then converted from a freehandobject to a rectangle object with height and width matching those drawnby the user. Within the application a rectangle is represented by aclosed polygon shape element and a rounded corner rectangle isrepresented by a closed curve shape element.

To draw an ellipse the user draws an ellipse in the drawing field, andthen draws a lasso starting from the ellipse icon and circumscribing thehand-drawn ellipse. The ellipse is then converted from a freehand objectto an ellipse object with height and width matching those drawn by theuser.

To draw a polyline the user draws a polyline in the drawing field, andthen draws a lasso starting from the polyline icon and circumscribingthe hand-drawn polyline. The polyline is then converted from a freehandobject to a polyline object. Within the application a polyline isrepresented as an open polygon i.e. a polygon shape element with anumber of points and with the start point being different from the endpoint.

To draw a polygon the user draws a polygon in the drawing field, andthen draws a lasso starting from the polygon icon and circumscribing thehand-drawn polygon. The polygon is then converted from a freehand objectto a polygon object.

To draw a curve the user draws curve in the drawing field, and thendraws a lasso starting from the curve icon and circumscribing thehand-drawn curve. The curve is then converted from a freehand object toa curve object, comprising a number of Bézier segments (see “3D ComputerGraphics”, Alan Watt, referred to above. The user can also create acurve by smoothing a polygon using the <Smooth> command.

Stock Objects

A user can include stock objects in their drawing, and these stockobjects can be selected, using a suitable available netpage selectionmechanism, and pasted onto the drawing field. Stock objects may beobtained from a stock object palette provided by the drawingapplication, or may be obtained from another application. Stock objectsinclude images and clip-art.

PAINTING VERSUS DRAWING

The painting application is a variation on the drawing application inwhich, in addition to a nib style, the user can also select a brushstyle, giving a richer selection of stroke styles.

Nib rotation and nib angle are important attributes in both drawing andpainting. Nib pressure is also important for a painting application, toallow the brush stroke appearance to vary based on the pen pressureapplied by the user. The painting application can simulate the visualeffects of interactions between overlapping brush strokes, and between abrush stroke and the canvas, and this can include taking into accountsimulated physical characteristics of both the paint and the canvasmedia.

CHANGING THE NIB STYLE

As explained above, a netpage pen 801 is a pen or stylus registered withthe netpage system, each netpage pen 801 having a unique id 61. Each penhas a current nib 824, being the nib last notified by the pen to thesystem, and a current nib style 825, being the nib style last associatedwith the pen by an application, e.g. in response to the user selecting acolor from a palette. The default nib style is the nib style associatedwith the current nib 824, and strokes 875 captured through a pen aretagged with the current nib style. When the strokes are subsequentlyreproduced, they are reproduced in the nib style with which they aretagged.

A netpage pen 801 may have interchangeable nibs to give the user theability to change the marking nib. This pen with interchangeable nibs isdescribed in further detail in our co-filed application U.S. Ser. No.09/693,341. When the user attaches a new nib to the netpage pen, the penobtains the nib id from the nib and notifies the system of the changednib id. The system uses the nib id to look up the nib style, and thepen's nib style attributes are set to match the characteristics of thenew nib. Subsequent user selections from the pen style palette willoverwrite these nib style settings.

A netpage universal pen, described in further detail in further detailin our co-filed application U.S. Ser. No. 09/693,216, contains aprinthead. The user selects pen/brush style attributes from a palette,thus updating the current nib style. The pen then faithfully reproducesa stroke which reflects current nib style attributes. Subsequent userselections from the pen style palette will overwrite the nib stylesettings and change the stroke style produced by the pen.

NIB STYLE SETTING REQUEST

A user can set nib style attributes (shape, size, color and opacitytextures) from the drawing and painting application. These attributesare recorded against the current netpage pen being used. When a useractivates a hyperlink to set the nib style, the page server 10 uses thepen id 61 to obtain the corresponding user id 60 from the registrationserver 11. It then builds a hyperlink request which records the ids ofthe requesting pen, user and printer, and identifies the clickedhyperlink instance.

When the application receives the hyperlink request from the pageserver, it may then choose to return a nib style request to the pageserver. The nib style request 542 includes the hyperlink request id 52for the original hyperlink click, the application id 64, and theapplication's nib style request 542. The nib style request 542 specifiesthe nib style attributes to be recorded against the current netpage pen801.

The page server 10 uses the hyperlink request id 52 to look up the userid 60 and pen id 61 of the original hyperlink request. The page serversends a nib style request 542 to the registration server 11, containingthe user id, application id, pen id, and nib style request. Theregistration server records the requested nib style attributes for therelevant netpage pen. The registration server then sends a message 543to the application 71 to confirm that the nib style request has beencompleted. The nib style setting protocol is shown in FIG. 18.

CONCLUSION

The present invention has been described with reference to a preferredembodiment and number of specific alternative embodiments. However, itwill be appreciated by those skilled in the relevant fields that anumber of other embodiments, differing from those specificallydescribed, will also fall within the spirit and scope of the presentinvention. Accordingly, it will be understood that the invention is notintended to be limited to the specific embodiments described in thepresent specification, including documents incorporated bycross-reference as appropriate. The scope of the invention is onlylimited by the attached claims.

1. An input unit arrangement for controlling an electronic device,comprising: a base; a position-coding pattern provided on said base andcoding a first and second sets of absolute positions on spatiallyseparate areas of said base; said first and second sets of absolutepositions being mutually exclusive and coded by spatially separate firstand second subsets of said position-coding pattern; a handheldimage-recording device for recording images of said position-codingpattern; and a processor for deriving at least one position from theposition coding pattern in the recorded image, said processor providingan instruction to the electronic device to perform a first function whensaid at least one absolute position belongs to the first set, and asecond function when said at least one absolute position belongs to thesecond set.
 2. The input unit arrangement of claim 1, wherein saidelectronic device, when instructed to perform said first function,interprets said at least one absolute position as at least one cursorposition.
 3. The input unit arrangement of claim 1, wherein saidelectronic device, when instructed to perform said first function, mapssaid first set of absolute positions to corresponding absolute positionsin a page description of said base.
 4. The input unit arrangement ofclaim 1, wherein said second function is an input function of the inputunit arrangement.
 5. The input unit arrangement of claim 4, wherein saidinput function is a recording handwriting function.
 6. The input unitarrangement of claim 5, wherein said processor, in said handwritingrecording function, records a handwriting stroke as a sequence ofabsolute positions derived from said images.
 7. The input unitarrangement of claim 1, wherein said second function is a controlfunction.
 8. The input unit arrangement of claim 7, wherein said controlfunction is selected from the group consisting of: displaying a graphicgrid; displaying one or more handles for manipulating a graphic element;auto-arranging one or more graphic elements; a pen shape; a pen size; apen texture; a pen color; a fill color; a fill pattern; a text font; atext font size; and a text font style.
 9. An interactive substrate foruse in an input arrangement having an input sensor reading aposition-coding pattern and providing a signal to an electronic deviceto provide instruction thereto, said substrate comprising: a base; aposition-coding pattern provided on said base and coding a first andsecond sets of absolute positions on spatially separate areas of saidbase, said first and second sets of absolute positions being mutuallyexclusive and coded by spatially separate first and second subsets ofsaid position-coding pattern; said first and second subsets of absolutepositions being associated with first and second functions of saidelectronic device to perform the function selected by use of the inputsensor.
 10. The substrate according to claim 9, further comprising avisual indication provided on said base in association with each of saidfirst and second subsets, said visual indication illustrating the firstand second functions, respectively.
 11. The substrate according to claim9, wherein said second function is a control function generating acommand for controlling the electronic device.
 12. The input unitarrangement of claim 11, wherein said control function is selected fromthe group consisting of: displaying a graphic grid; displaying one ormore handles for manipulating a graphic element; auto-arranging one ormore graphic elements; a pen shape; a pen size; a pen texture; a pencolor; a fill color; a fill pattern; a text font; a text font size; anda text font style.
 13. The input unit arrangement of claim 9, whereinsaid electronic device, when instructed to perform said first function,interprets said at least one absolute position as at least one cursorposition.
 14. The input unit arrangement of claim 9, wherein saidelectronic device, when instructed to perform said first function, mapssaid first set of absolute positions to corresponding absolute positionsin a page description of said base.
 15. A method for controlling anelectronic device between a first and a second function, using ahandheld image recording device interacting with a position-code patterncomprising: operating the handheld image-recording device for recordingimages of the position-coding pattern provided on a base, the positioncoding pattern coding a first and second sets of absolute positions onspatially separate areas of the base; said first and second sets ofabsolute positions being mutually exclusive and coded by spatiallyseparate first and second subsets of said position-coding pattern, andoperating a processor for processing the images to derive at least oneposition from the position coding pattern in the recorded image,providing an instruction to the electronic device to perform a firstfunction when said at least one absolute position belongs to the firstset, and a second function when said at least one absolute positionbelongs to the second set.
 16. The method according to claim 15, furthercomprising: operating said processor to control said electronic deviceto effect at least one of the first and second functions based on saidimages.
 17. The method of claim 15, wherein said electronic device, wheninstructed to perform said first function, interprets said at least oneabsolute position as at least one cursor position.
 18. The method ofclaim 15, wherein said electronic device, when instructed to performsaid first function, maps said first set of absolute positions tocorresponding absolute positions in a page description of said base. 19.The method of claim 15, wherein said second function is an inputfunction of the input unit arrangement.
 20. The input unit arrangementof claim 19, wherein said input function is a recording handwritingfunction.